Machines for stacking limp work pieces

ABSTRACT

1. A MACHINE FOR STACKING FLEXIBLE WORK PIECES, COMPRISING A RELATIVELY MOVABLE WIPER BLADE AND HOLD-BACK MEANS, THE WIPER BLADE BEING CARRIED BY AN OSCILLATORY LEVER AND THE HOLD-BACK MEANS BEING CARRIED BY AN OSCILLATORY MEMBER OPERABLE SUBSTANTIALLY IN PHASE WITH SAID LEVER, THE TURNING RADIUS OF THE BLADE BEING GREATER THAN THAT OF THE HOLD-BACK MEANS, MEANS FOR JOINTLY MOVING THE BLADE AND HOLD-BACK MEANS, RESPECTIVELY, BETWEEN A WORK RECEIVING POSITION AND A DELIVERY POSITION WHEREIN EACH PIECE IS TO BE STACKED, AND MECHANISM FOR CAUSING THE HOLD-BACK MEANS INITIALLY TO ENGAGE EACH WORK PIECE AT SAID WORK RECEIVING POSITION AND THEN RELATIVELY ADVANCE THE WIPER BLADE LENGTHWISE OF THE WORK PIECE AND AWAY FROM THE HOLD-BACK MEANS DURING THEIR MOVEMENT TOWARD SAID DELIVERY POSITION TO CAUSE THE TRANSFERRED WORK PIECE TO BE OUTSPREAD LENGTHWISE FOR DEPOSIT ON THE STACK.

United States Patent [1 1 Fuller, Jr. et a1.

[ MACHINES FOR STACKING LIMP WORK PIECES 7131' a ez USM 95299921fiqslqntMeseV [22] Filed: Mar. 22, 1972 [21] Appl. No.: 236,878

2,754,119 7/1956 Morgan et al. 271/68 X 3,163,415 12/1964 Atchison et a1 271/68 2,737,390 3/1956 Morgan et a1. 271/68 Primary Examiner-Evon C. Blunk Assistant Examiner-James W. Miller Attorney, Agent, or Firm-Carl E. Johnson; Vincent A. White; Richard B. Megley [57] ABSTRACT Cyclically operating mechanism including a hold-back means intercepts a pendant lead portion of each successively advancing work piece, and during oscillation of the hold-back means about a horizontal axis and while traveling toward stacking position, a work spreader or wiping member extends to spread out the work piece and then deposits it predeterminedly. The mechanism preferably is operated by fluid pressure and the hold-back means and wiping member are usually actuated synchronously in phase. A counting means may be associated with the stacking mechanism for automatically shifting each stack to an out-of-theway position when a predetermined number of units have been assembled.

9 Claims, 4 Drawing Figures MACHINES FOR STACKING LIMP WORK PIECES CROSS REFERENCE TO RELATED APPLICATION BACKGROUND OF THE INVENTION Handling and positioning of successive limp, work pieces, when done manually, becomes tedious and boring. Various approaches to providing mechanical solution of the problem have been made. Since the different sizes, shapes and character of the flexible work pieces to be transferred are many, it has proven difficult to provide automatic, reliable transfer mechanism for dealing with them all. The present invention is especially concerned with providing a dependable, quietly operating mechanism for cyclically receiving a flexible sheet-like work piece, for instance a piece of fabric such as a towel or garment part, as it exits from another machine or a conveyor and then carrying and spreading the piece into horizontal delivery position in alignment with previously deposited and stacked work pieces.

Mechanism hitherto employed for transferring sheet material has often depended upon vacuum cups or the like and associated complex controls. Also, the known stackers have often required excessive operator attention and at times been noisy and apt to damage or soil the work.

SUMMARY OF THE INVENTION In view of the foregoing, it is a main objective of this invention to provide a relatively uncomplicated yet reliable machine for transferring successive flexible work pieces from a receiving position and delivering them in a fully outspread condition to a positioned generally aligned with a stack.

Another objective of the invention is to provide, for use in conjunction with the delivery end of a conveyer or an exit zone of a processing machine, a stacker having mechanism movable to deliver each work piece onto a stack and, when the stack contains a predetermined number of pieces, will shift the completed stack to allow another one to be accumulated without interruption of the mechanism.

To these ends preferably, and as herein illustrated, there is associated with an oscillatory sheet carrying means controlled by fluid pressure, a mechanism for gently cushioning the delivery strokes of the carrying means, and a sheet wiping mechanism automatically extendable relative to hold-back means during the delivery stroke to insure that the transferred sheet is released outspread upon a stack.

BRIEF DESCRIPTION OF THE DRAWINGS The foregoing and other features of the invention together with novel details in construction will now be more particularly described in connection with an illustrative embodiment and with reference to the accompanying drawings thereof, in which:

FIG. 1 is a view in side elevation, with portions broken away, and showing sequential positions of parts of a machine for stacking flexible work pieces.

FIG. 2 is a view in end elevation of the machine of FIG. 1, its hood being removed, as seen when looking from the right;

FIG. 3 is a schematic diagram of the electrical control system; and

FIG. 4 is a schematic diagram of the pneumatic controls, the work transfer means being in delivery or down position.

DESCRIPTION OF PREFERRED EMBODIMENT Referring to FIGS. 1 and 2, a rectangular main frame designated 10 has a horizontal elongated platform 12 adapted slidably to hold successive work pieces W to be stacked in generally aligned stacks S. One end of the frame 10 is journalled to rotatably support a cross shaft 14 to the ends of which there is respectively secured, as by a clamping bolt 16, the lower ends of oscillatory actuating levers l8, 18. Each of the upper ends of the levers 18, 18 has ball and socket connection by means of links 20, 20 with the respective ends of a laterally extending wiper blade 22 which, by means to be described, is caused to be swung from a generally vertical initial work engaging position through an arc usually less than to a more nearly horizontal position wherein a work piece W is to be released to a stack S on the platform 12. An open-sided hood 24 mounted on the frame 10 guards against unwanted interference with the mechanism and supports centrally a photocell sensing means 26 (FIGS. 1, 3) responsive to the arrival of a leading depending portion of each work piece W to be transferred and stacked.

As shown in FIG. 1 the arrangement is such that the leading dependent portion of a work piece will be engaged by an oscillatory and synchronously phased holdback means generally designated 30 and cooperative wiper blade 22 to insure that in the course of transfer to delivery position each work piece is unfurled and made substantially straight and properly ordered with respect to the stack. The hold-back means 30 is preferably comprised of high-friction elements such as card cloth units 32 carried at laterally spaced points by a plate 34 which is oscillated with a skeletal swing frame 36 (FIG. 2). Preferably the plate 34 is formed with openings 38 (FIG. 2) to reduce weight and air resistance. The frame 36 includes cross braces 40,42 diagonal members 44,46 connecting the braces 40,42, and opposite side bars 48,48 also connecting the cross braces 40,42. The lower ends of the side bars 48 are pivoted on coaxial pins 50,50 respectively supported by side plates 52,52 of the frame 10.

For operating the hold-back means 30 in phase relation to the transfer strokes of the wiper blade 22, and for operating the latter, the mechanism next to be described is provided. A cylinder 54 (FIGS. 1, 2 and 4) pivotally secured to the frame 10 at pin 56 has a dualacting piston rod 58 an end of which is pivotally connected to the one of the levers l8. Fluid pressure, preferably pneumatic, is accordingly directed to one side and then the other of a piston (shown only in FIG. 4) of the cylinder 54 to oscillate the wiper blade 22 between substantially vertical work engaging position and a horizontal delivery position as shown in FIG. 1. A hold-back actuating rod 60 secured at its upper end by a set screw 62 to the wiper blade 22 is longitudinally slidable in aligned bearing blocks 64, 64 in the cross braces 40, 42 respectively. Accordingly, in the interval that the wiper blade 22 moves angularly downward about the axis of the shaft 14, the hold-back units 32, having frictionally engaged the lead marginal portion of a work piece, more angularly about the pins 50,50 on an are having a shorter radial length. Hence, the units 32, which initially were extending above the blade 22, are relatively retracted with respect thereto during the synchronous delivery strokes of the levers 18,18 and the side bars 48,48 so that the work piece is progressively inverted and straightened as it is drawn about the wiper blade 22 and outspread as it descends. The wiper actuating rod 60 as it is swung downwardly is in fact projected lengthwise relative to the hold-back means 30. While in their vertical positions the links and the blade 22 are generally aligned with the levers 18, and in the projected or more horizontal position of the rod 60, the links 20 are angularly related to the levers 18, due to the tension which has been applied to the blade through the work piece W, to enable the trailing portions of the transferred work piece to be outspread and finally relaxed for release and deposit in parallel relation to the top of the stack S. In the course of relatively separating the hold-back means and the wiper blade to straighten out the work during work transfer, the bristles of the units 32 hold the marginal portion of the work against slipage and generally and biased to grip more securely in resisting the tension being exerted on the work by the unfurling action of the arcuately descending blade 22. Upon nearing the end of each delivery stroke, the links 20,20 are positively caused by the rod to assume a broken toggle relation to the arms 18 as above indicated; this, plus the fact of simultaneous reversal of both the blade 22 and the hold-back means 30 effectively releases the transferred work piece for deposit on the top surface of the stack S.

Buffer mechanism next to be described is provided for absorbing shock'and cushioning the terminal motion of the work transfer mechanism both in its vertical pickup zone and horizontal delivery zone. For this purpose a pneumatic cylinder 66 (FIGS. 1, 2 and 4) having one end secured to the frame 10 has a double-acting piston rod 68 secured by a coupling 70 to one endof an extention rod 72. The latter carries resilient stops 74,76 respectively arranged to be engaged at the initial or upper work receiving position and at the more horizontal delivery position by a telescoping slider block 78 carried by a pin 80 (FIG. 2) secured in the adjacent lever 18. Referring to FIGS. 1 and 4, when line pressure is directed through a pressure regulating valve CC and via a line 82 to an end of the stacker actuating cylinder 54 thereby causing its piston rod 58 to swing the blade 22 and the hold-back means 30 counter-clockwise (as seen in FIG. 1) to vertical positions, fluid pressure is also applied via a line 84 and valve BB to an end of the buffing cylinder 66 which has a diameter smaller than that of the cylinder 54. Accordingly as the unloaded work transfer mechanism approaches the vertical disposition, the slider block 78 will engage the stop 74 and meet with yieldable but increasing resistance opposing displacement of the buffer piston rod 68 to the right as seen in FIG. 4. Exhaust of the cylinder 54 is via a line 86, a pressure regulator valve DD and the valve V-S, the buffer cylinder 66 exhausting via a line 88, a regulator valve AA and the valve V-S.

Similarly 'in connection with a delivery stroke, pressure fluid is admitted to the other-end of the actuating cylinder-54 (action which is initiated by the sensor 26 detecting arrival of the margin of a work piece W to be stacked and energizing the solenoid 5-5) when the valve V-S shifts to pressurize the line 86 through the valve DD. Now the slider block 78 moves from the block 74 to engage the block 76 which meets with increasing resistance to leftward displacement (as seen in FIG. 4) by reason of concurrent buildup of pressure fluid introduced into an end of the smaller cylinder 66 via the valve AA and the line 88. The counterbalancing pressures provided in the cylinder 66 thus insure that terminal motion of the cyclical transfer mechanism is neither harsh nor noisy.

An automatic stack shifting mechanism generally designated (FIGS. 1, 2 and 4) will next by explained. Secured by brackets to the platform 12 is a stationary cylinder 102 having a dual-acting piston rod 104. A valve V-6 controlled by a solenoid 5-6 will be explained admits air under pressure to the left hand end of the cylinder 102, as seen in FIG. 1, to shift the rod 104 and transverse pusher blade 106 secured thereto, by a bracket 108 projecting through a slot in the platform 12, to the right thereby displacing an accumulated stack S from its solid line position to the dash line position and enabling a new stack to be accumulated. The arrangement as shown desirably includes in its electrical controls as will be described with reference to FIG. 3 a counting means for insuring that when the higher of two predetermined numbers of work pieces have been stacked, the pusher plate will slide the stack to an out-of-the-way position on the platform 12 and then return to a position in readiness to transfer the next stack. A counter 110 (FIG. 3) is set to actuate upon a predetermined lower number of work pieces being accumulated, and a counter l 12 actuates when the larger number is stacked. The arrangement is such that when the lower number has accumulated, a new and safely higher release point is established.

A cycle of operations will next be described with particular reference to FIG. 3. Upon arrival over the hood 24 from a machine or conveyor, a work piece W to be stacked is detected by the photoelectric control 26 (FIGS. 1 and 3), and its output contacts 26CR (FIG. 3) responsively change state. The contacts 26CR close and energize relay lCR which latches in 'if the stacker and stack shifting means 100 are in their return positions. Hence contacts lCR energize the stack control solenoid S-5 and causes both counters 110 and 112 to increment as the hold-back means 30 and cooperating blade 22 separate and descend to the delivery positions. The clockwise rotation of the arms 18 to the lower limit of their delivery stroke will coincide with actuation of a limit switch 3LS (FIGS. 2 and 3) by an arm 114 secured on the shaft 14. The switch 3LS hence deenergizes the relay lCR which, in turn, deenergizes the stack solenoid S-S allowing the arms 18, the wiper blade 22, and the hold-back means 30 to be raised to return or work receiving position wherein limit switch ILS is actuated by an arm 115 on the shaft 14. The counter 110 will change state after a lower predetermined number of work pieces have been deposited in a stack S and thereby allow the stacker blade 22 and hold-back means 30 to return to vertical position after they can not descend to actuate the switch 3LS but do descend sufficiently to actuate a limit switch 2LS (FIGS. 2, 4) by means of an arm 115 fixed on the shaft 14. This permits stacking a higher pile and avoids releasing bottom sheets from too high a release point above the stack.

After stacking the desired number of work pieces W, the counter 112 will change state and energize relay 2CR thereby resetting the counters 110, 112. The stack shifting solenoid 8-6 is actuated after the last of the predetermined number of work pieces has been deposited and the stacker is in the vertical or return position. Hence the pusher plate 108 will move to the right in FIG. 1 to clear the fully accumulated stack 5 and actuate a limit switch 4LS (FIGS. 3 and 4). The latter causes the plate 18 to be returned by the cylinder 102 to its initial or left most position shown in FIG. 1 preparatory to further stacking. It will be apparent that for stacking different sizes of flexible articles the stroke of the cylinder 102 and the position of limit stops may be suitably adjusted.

From the foregoing it will be clear that the invention provides an automatic and non-complicated doffing mechanism whereby successive work pieces are turned over and repositioned in uniform manner on a stack until a desired quantity is stacked whereupon the pile is shifted on the platform to enable further stacking to continue. The operator accordingly can largely direct his attention to the machine from which the work pieces are being received and/or to the removing of the stacks from the platform 12.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent of the United States is:

l. A machine for stacking flexible work pieces, comprising a relatively movable wiper blade and hold-back means, the wiper blade being carried by an oscillatory lever and the hold-back means being carried by an oscillatory member operable substantially in phase with said lever, the turning radius of the blade being greater than that of the hold-back means, means for jointly moving the blade and hold-back means, respectively, between a work receiving position and a delivery position wherein each piece is to be stacked, and mechanism for causing the hold-back means initially to engage each work piece at said work receiving position and then relatively advance the wiper blade lengthwise of the work piece and away from the hold-back means during the movement toward said delivery position to cause the transferred work piece to be outspread lengthwise for deposit on the stack.

2. A machine for stacking flexible work pieces comprising a frame, a sensor on the frame responsive to successive work pieces to be stacked, and transfer mechanism controlled by the sensor and oscillatory between an upper initial work engaging position and a lower delivery position, said transfer mechanism including a wiper blade disposed transversely of the work and oscillatory about a first axis in the frame, and a hold-back means oscillatory about a second axis in the frame parallel to said first axis, and mechanism for causing the blade progressively to invert and spread out lengthwise a work piece marginally restrained at one end portion by the hold-back means as the piece is transferred to said delivery position, the last mentioned mechanism including a power device operatively connected to the blade to move it between limits, and a member having connection to the blade and slidable in bearings in the hold-back means to synchronously operate the latter with the blade.

3. A machine as in claim 2 wherein said power device includes a fluid pressure operated piston-cylinder, and a lever pivoted to the frame for driving the blade and actuated by the piston-cylinder device.

4. A machine as in claim 3 wherein another lever is operated in phase with said blade-driving lever about a coaxial pivot in the frame, and corresponding ends of the two levers are connected, respectively, to the blade by toggle links.

5. A machine as in claim 2 wherein the first axis is substantially in vertical alignment with said second axis.

6. A machine as in claim 3 wherein said blade-driving piston-cylinder is dual-acting, and a second dual-acting piston-cylinder is of smaller diameter and connected to partake of fluid pressure directed toward the blade' driving cylinder for cushioning terminal motion of the blade and hold-back means.

7. A machine for stacking flexible work pieces comprising a main frame providing an upper work receiving surface and a lower work supporting surface, a work transfer mechanism mounted on the frame and movable between said upper and lower surfaces, said mechanism including a hold-back means and a wiper blade extending in generally parallel relation, power means cyclically operable to shift the hold-back means and the blade synchronously between work receiving and delivery positions respectively adjacent to the upper surface and the lower surface, said power means being adapted to cause a margin of each work piece being transferred to be restrained by the hold-back means as the blade is relatively projected lengthwise of the holdback means during descent to spread out the piece for deposit on the lower surface, and a control circuit for said power means having a counting means including two limit switches for insuring that when the deposited work pieces accumulate to a predetermined lower level determined by the position of one of said switches, the lower limit of travel and work release of said transfer mechanism is shifted upwardly to an upper work release position above the accumulated stack.

8. A machine as in claim 7 wherein the work transfer mechanism is oscillatory about a shaft, and said two limit switches are actuable by angularly spaced members mounted on said shaft.

9. In a stacker of the type having oscillatory work transfer means, said means including a high friction hold-back and a wiper parallel thereto, a first fluid pressure operated dual-acting piston-cylinder device for cyclically moving the work transfer means between pickup and delivery positions, valve means for alternately pressurizing opposite ends of the cylinder of the first device, and a second fluid pressure operated dualacting piston-cylinder device operatively connected to receive fluid pressure via said valve means to cushion the work transfer means as it nears the ends of each oscillation. 

